// 常用系统调用
fn syscall_call6(int number, cptr a1, cptr a2, cptr a3, cptr a4, cptr a5, cptr a6):int

fn syscall_exec(string path, [string] argv, [string] envp)

fn syscall_getcwd():string

fn getenv(cptr key):cptr

fn setenv(cptr key, cptr value, i32 overwrite):i32
